Accurate shot taking is the goal of all archers, whether they are in a hunting or a target shooting environment. Over the years, several bow sights have been developed to aid the archer in accurate shot placement. The prior art consists of a variety of methods by which an archer attempts to compensate for the increase in arrow trajectory with increasing target distance. Generally, this has been accomplished by mounting sight pins on the bow such that the end of the pin is in the same vertical plane as the arrow and the bow string. By adjusting these sight pins vertically, relative to the bow, an angle is formed in the vertical plane between the arrow and the sight line from the archer's eye through the end of the sight pin to the target. The great variation between types and strengths of bows and the differing aerodynamic properties of arrows has lead to sight pins being set in position by experimental means: the archer uses a target at a known distance and calibrates the bow sight by aligning the sight pin with the target and shooting. By this method the sight pin is fixed relative to the bow for the specific target range. A number of sight pins can be fixed by similar means to give the archer a number of target distance options. Most bow sights require the archer to remember which sight pin represents a particular target distance.
In addition to the sight pin, all archers try to establish an "anchor point" when the bow string is fully drawn. A constant anchor point creates a repeatable sighting geometry. A constant full draw anchor point ensures that the sight pin position the archer has established remains accurate. For example, a bow which is drawn to varying degrees will produce varying arrow speeds and, consequently, varying target ranges.
The anchor point is established by use of devices which attach to the bow string. The `kisser` button is a small button shaped device fixed to the bow string such that the string passes through the center of the button and perpendicular to it. The kisser button is unaffected by any twisting of the bow string. The kisser button is positioned such that it contacts the archer's face, usually the lip or chin, in the same place for every draw of the bow.
An alternative to the `kisser` button is a string peep. A string peep is a device by which an aperture can be set into the bowstring such that it aligns with the archer's eye at full draw. The string peep is used as a rear sight which is aligned with the front sight pin to accurately aim the bow. The string mounted peep sight is seen in a variety of shapes and designs. However, the general configuration is that of a disk having a peep hole in the center attached to the bow string at a point on the bow string that it lines up with the archer's eye at full draw.
The string peep has several disadvantages both in general use and more particularly in low light conditions. It can and does twist when the bow is drawn. It can create bad shooting form by encouraging the archer to draw the peep closer to the eye without giving any indication of this circumstance to the archer. The range of apertures and the closeness of the peep to the eye often allow more than one distance sight pin to be seen within the peep. This negates the peep's usefulness for sighting purposes because the archer must select a single pin for the required range. The disconnect between the string peep and the body of the bow allows the bow to be twisted about vertical (wrist torque) and horizontal axes without any indication to the archer. All sights which incorporate single point bow mounted sight pins are susceptible to this problem. For example, a string mounted peep sight is generally unpredictable in that it is usually never in the proper viewing position when at full draw. Due to its method of attachment, the bow string mounted peep sight often turns in different directions when the user pulls the bow to a full draw. Further, string mounted peep sights are prone to clogging with debris and can, therefore, hamper the user's ability to use the sight when necessary. Perhaps the greatest drawback to string mounted peep sights is that they are difficult to view through during low light conditions. This is particularly troublesome inasmuch as periods of low light, such as dawn and dusk, are ideal for hunting.
Attempts to overcome these difficulties are seen in the prior art in the form of bow mounted sights. For example, U.S. Pat. No. 5,559,780 discloses a bow mounted sight assembly having a range finder. The sight pin is mounted on a sight arm which, in turn, is designed to rotate about a pivot in direct proportion to the movement of a vertical member which is connected to the range finder. The user sights the target by manipulating the vertical member while sighting the sight pin onto the target. The range finder at the top of the device will then indicate a range to target. This device, however, represents a sight which provides only a single sight pin, and, therefore, requires that the user sight the pin directly to the target while manipulating the vertical arm until a supposed accurate sight is made. Hence, a one-position sight is provided, but the one-position consists of the one forward sight pin which is moveable by the user, and sights directly to the target. It has been found that such sight assemblies are less than accurate and capable of error.
A further example is disclosed in U.S. Pat. No. 5,001,837 which is directed to a bow mounted sight assembly having a range finder and peep sight all mounted to a forwardly extending sight assembly. The peep assembly is moveable by means of an arm carrying a lower finger control at the bottom. The device is constructed as a parallelogram such that the movement of the peep sight will move the range finder, which is located on the top portion of the unit, until a range is determined to target. As disclosed, the entire sight assembly moves forward of the bow since it is mounted on a bracket, which is, in turn, mounted to the bow. This is intended to provide adjustment capabilities. It should be noted, however, that the entire sight assembly includes numerous moving parts, and still provides only a single peep through which the user views the target in order to sight the range. It should be further noted that once the user sights the target, a locking bolt with a handle is then utilized to lock the parallelogram subassembly into a fixed orientation in order to "lock on the target". It has been found that manipulating such a sight assembly is difficult for the user, and requires several hand manipulations in order to sight the target. Further, it is difficult to lock the unit into position once the user is at full draw. In summary, the sight assembly as described provides a sight assembly which has a moveable forward peep sight as the sole sight means for sighting a target.
Yet another example is found in U.S. Pat. No. 5,092,052 which discloses a bow mounted sight having a moveable peep sight for sighting the target. This device includes a bow handle mounted bracket having a forwardly moveable peep sight. Use of this device requires the user to move a rear lever throughout a curvilinear track, which then translates motion to the forward moveable peep sight along a vertical track such that the rotary movement of the rear lever translates to vertical movement of the peep sight. Once again, this sight provides a single peep sight for sighting a target and requires the user to use a single sight window or peep sight for sighting the target. Further, the moveable portion of the sight is located on the forward end of the sight assembly, and is therefore further removed from the eye of the user.
Innovations in bow sight technology have focused on sights with a single floating sight pin which is adjustable for various target distances, as seen in U.S. Pat. No. 5,092,052. The advantage of these sights is that they eliminate confusion as to which sight pin is correct for the target distance. A single pin is moved vertically on the front of the sight while the rear of the sight acts as a range indicator. The range indicator is calibrated experimentally. These sights, however, are used in conjunction with a string peep sight or kisser button and do not solve the problem of twisting the body of the bow.
A further improvement is described and claimed in a related application for an improved bow sight filed in the names of Vanderheyden and Sweeney under Ser. No. 08/600496 and owned by Assignee Hurckman Mechanical Industries, Inc. That application describes a two-point bow mounted sight assembly. The sight assembly has a main sight body having a forward portion and a rear portion. The forward portion of the sight body contains several vertical slots into which stationery sight pins are inserted in predetermined locations specific to certain sight distances. The rear portion of the sight body contains a peep sight moveable along a curvilinear track. Movement of the peep sight is caused by an interlocking sight adjustment lever. Located on the rear wall of the curvilinear track is a distance indicator. In use, an archer locates a target through the peep sight and intersects the peep sight with the sight pin closest in accuracy to the distance indicated on the distance indicator. Thus, a more accurate two-point sighting is effectuated than when using a one-point sight. While being a vast improvement over the prior art, the drawback to this device is that it is accurate only in those circumstances in which the target is the exact distance away from the user of pre-selected sight pin.
The addition of a second sighting point mounted on the main body of the bow totally eliminates the potential for twisting. Any movement is indicated clearly by the misalignment of the two sighting points.
The present bow sight is a further improvement over the aforementioned bow sight as will be understood in connection with the following description.